Liquid fuel pumps



Nov. 26, 1968 K. A. w. KEMP 3,412,682

LIQUID FUEL PUMPS Filed March 26, 1965 3 Sheets-Sheet l Nov. 26, 1968 K.A. W. KEMP LIQUID FUEL PUMPS 3 Sheets-Sheet 2 Filed March 26, 1965 Nov.26, 1968 K. A. w. KEMP LIQUID FUEL PUMPS Z5 Sheets-Sheet 5 Filed March26, 1965 NN M United States Patent 3,412,682 LIQUID FUEL PUMPS KennethAlbert Walters Kemp, London, England, assignor to CAN. Limited, London,England Filed Mar. 26, 1965, Ser. No. 443,027 Claims priority,application Great Britain, Mar. 31, 1964, 13,099/ 64 3 Claims. (Cl.103-2) ABSTRACT OF THE DISCLOSURE The invention relates to liquid fuelpumps for supplying fuel to an internal combustion engine and of thekind comprising a body part, an injection pump mounted within the bodypart and operable in timed relationship to an engine with which the pumpis associated, and a passage within the body part through which fuel canbe supplied to the injection pump during each filling stroke thereof,said passage being in communication with a source of fuel the pressureof which is dependent upon the speed of rotation :of the engine.

The object of this invention is to provide such a pump in a simple andconvenient form.

According to the invention a pump of the kind specified includes acylinder formed in the body part, one end of said cylinder being incommunication with said source, a plunger slidably mounted in saidcylinder, the position of said plunger serving to control the flow offuel through said passage, resilient means urging said plunger towardssaid one end of the cylinder, a restriction through which the outer endof the cylinder is in communication with said source, and valve meansoperable to allow fuel to escape from the other end of the cylinder, thearrangement being such that when said valve means is operated thepressure of fuel in said other end of the cylinder will be reduced andthe position of the plunger, and

hence the quantity of fuel flowing through the passage, will bedetermined by the pressure of fuel acting on the end of the plunger inopposition to the force exerted by the resilient means, and when saidvalve means is not operated the pressure of fuel at the opposite ends ofthe cylinder will be substantially the same and the position of theplunger will be such as to allow a maximum quantity of fuel to flowthrough said passage.

In the accompany drawings:

FIGURE 1 is a sectional side view of one example of a liquid fuel pumpincorporating one example of the invention,

FIGURE 2 is a plan view of part of the pump shown in FIGURE 1,

FIGURE 3 is a sectional view taken on the line 33 of FIGURE 1,

FIGURE 4 is a sectional view taken on the line 4-4 of FIGURE 1,

FIGURE 5 is an enlarged scrap view of part of the pump shown in FIGURE1,

FIGURE 6 is a scrap view of part of the pump shown in FIGURE 1,

FIGURE 7 is a diagrammatic view of a tractor transmission mechanism Iandengine, and

FIGURE 8 is an enlarged view of the gear selector gate of thetransmission mechanism shown in FIGURE 7.

Referring to the drawings there is provided a body part 10 in which ismounted a rotary cylindrical distributor member 11 which is coupled toan input shaft 12 arranged to be driven in timed relationship to anengine 13 with which the pump is associated. Within the distributor isformed a transverse bore 14 in which are mounted a pair of reciprocableplungers 15 and which are arranged to be moved inwardly, as thedistributor rotates, through the intermediary of a pair of rollers 16respectively, by cam lobes (not shown) formed on an annular cam ring 17mounted for angular movement within the body. Also formed in thedistributor is a longitudinally extending passage 18 which at one end isin communication with the transverse bore and at its other end is incommunication with a radially disposed delivery passage 19 The deliverypassage 19 is arranged to register, in turn, with a plurality ofequi-angularly spaced delivery ports. constituted by passages 20, formedin the body part 10 and which :are adapted to be connected by pipe linesto injection nozzles 21 mounted on the engine. The aforesaidregistration with one of the ports takes place during the whole time theplungers 15 are being moved inwardly so that liquid fuel containedwithin the transverse bore 14 will be displaced to a combustion space ofthe engine.

At another point the longitudinal passage is in communication with aplurality of equi-angularly spaced and radially disposed inlet passages22 which are arranged to register, in turn with an inlet port 23 formedin the body part. The inlet port 23 is in communication with a controlport 25, by way of a passage 24, and the control port is incommunication with the outlet 26 of a feed pump 27.

Moreover, the effective size of the control port 25 can be varied byvarying the angular setting of a valve member 28 which has a grooveformed therein and the arrangement is such that when an inlet passage 22registers with the inlet port 23 fuel will flow from the outlet of thefeed pump to the transverse bore 14 to move the plungers 15 outwardly.The aforesaid registration takes place only during the time when thedelivery passage 19 is out of register with the passages 20 and duringthe time when the rollers 16 are clear of the cam lobes. By adjustingthe setting of the valve member 28 the rate at which fuel can flow tothe bore 14 can be controlled and hence also the amount of fueldelivered to the engine is controlled.

The feed pump 27 is provided with an inlet 29 in the body part and thisis in communication with an inlet port 30 formed in a hollow part 31secured to the body part. The part 31 has mounted therein a tubularfilter element 32 and a relief valve which includes a spring loadedelement 33. One end of the element 33 is exposed to the pressure of fueldelivered by the feed pump and controls the size of a spill port 34 andand arrangement is such that the feed pump always pumps more fuel thanis delivered to the engine with the result that the output pressure ofthe feed pump is controlled in a manner which is dependent upon thespeed of the engine and which increases with the speed thereof.

As previously mentioned the cam ring 17 is angularly adjustable to varythe time of delivery of fuel to the engine. This adjust-ment is achievedby a spring loaded piston 35, mounted in a chamber 36, and which isconnected to the cam ring by a radial peg 37. Fuel is supplied to oneend of the cylinder 36 to move the piston in opposition to its spring,from the outlet 26 of the feed pump, and since the pressure of fuel isdependent upon the speed of rotation of the engine, the angular settingof the cam ring and hence the timing of injection of fuel to the engineis also dependent upon the speed of the engine. The fit of the piston 35within the cylinder 36 is slack so that leakage occurs therebetween.Moreover, a check valve 38 inincorporated in the supply passage to thecylinder 36 and this closes to prevent fuel passing from the cylinder tothe supply passage due to the interaction of the rollers with the camlobe.

The angular setting of the valve member 28 is conveniently controlled bya mechanical governor which includes weights 39 which are mounted to berotated by the drive shaft 12, and which act on an axially movableflanged collar 40. The axial movement of the collar is resisted by agovernor spring 41 which is mounted between one end of a pivotal lever42. and an operator adjustable member 43, the other end of the lever 42bearing upon the collar. Furthermore, said one end of the lever isconnected by tie rod 44 to the member 28 and the arrangement is suchthat as the speed of rotation of the engine rises the collar 40 will bemoved axially by the weights against the action of the governor springand during this movement the member 28 will be moved angularly to reducethe quantity of fuel delivered to the engine. At some speed anequilibrium position will be reached and if the speed of the enginefalls, as for instance when an increased load is applied to the engine,the force applied to the collar by the weights will be reduced and themember 28 will be moved to increase the fuel supplied to the engine tocater for the extra load. The setting of the operator adjustable member43 can be varied to vary the force imposed by the spring 41 on the leverand by this means the governed speed of the engine may be varied.

The engine 13 to which the pump is fitted is as shown in FIGURE 7,intended to be used for driving the road wheels 45 of a road vehiclethrough a conventional axle unit and a multispeed gearbox 46.Furthermore, as shown in FIGURE 8, the gearbox is provided with aselector lever 47 which moves within a selector gate 48. When a vehicleis in use it is often desirable to be able to limit the speed of thevehicle when the selector lever is set in the high gear position, i.e.,when the speed of the engine is lowest for a given speed of the roadwheels, but it is also desirable that the speed of the engine should notbe limited when the selector lever is in one of its alternativepositions so that full power may be obtained from the engine andtransmitted to the road wheels as when negotiating a steep incline. Inorder to cater for this requirement means, which is described below, isembodied in the pump and said means is brought into operation by aswitch 49 mounted in the gearbox 46 and arranged to be operated when theselector lever 47 is moved to the high gear position.

Referring now to FIGURES 3, and 6, said means comprises a cylindricalbore 50 longitudinally disposed within the body part and whichintermediate its ends intersects the portion of the supply passage lyingintermediate the control and inlet ports. Moreover, within the bore isslidably mounted a plunger 51 having a reduced portion 52 intermediateits ends, and this lies when the plunger is in the inoperative positionas shown, in a position so that the iiow of fuel to the inlet port 23 isnot restricted. Furthermore, the plunger is loaded towards one end ofthe cylinder by a coiled compression spring 53 which is interposedbetween the plunger and an axially movable abutment 54 mounted in thebore. The axial setting of the abutment can be pre-set from the exteriorof the pump by an adjuster 55 having a tapered end which co-acts withthe adjacent tapered end of the abutment.

The end of the plunger 51 remote from the spring, when in theinoperative position, bears against a stop defined by a plug 56, andthis end of the plunger is arranged to be exposed to the outlet prsesureof the feed pump by way of a clearance defined between the plunger andthe bore. Moreover, the space intermediate the plunger 51 and theabutment 54 is in communication with the feed pump outlet by way of apassage 57 in the plunger and this passage incorporates a restriction57a. Furthermore, in the abutment 54 is formed an unrestricted passage58 which places the aforesaid space in communication with the space atthe end of the bore adjacent the tapered end of the abutment.

The end of the bore 50 adjacent the adjuster 55 is in communication withone end of a passage 59 in the body part 10, and the other end of thispassage communicates with the space in which the weights 39 areaccommodated, and this space communicates with a drain outlet 62. Thepassage 59 incorporates a valve intermediate its ends, and this includesa seating 60 and a closure member 61. The closure member as shown inFIGURE 3 is operable by an armature 63 movable by a solenoid 64. Thesolenoid is connected in circuit with the switch 49 and the latter is ofthe normally closed type. When the solenoid is deenergised the pressureof fuel acting on the closure member 61 moves it to allow fuel to flowthrough the passage 59.

In use, when the solenoid is energised the valve will be closed with theresult that the pressure in the chamber defined intermediate the plunger51 and the abutment 54 will be the same as the outlet pressure of thefeed pump. As a result the fuel pressure acting on the plunger will bebalanced and the plunger will be maintained in the position shown inFIGURE 5 by the spring 53. As previously stated, the flow of fuel to theinjection pump when the plunger is in this position is not restricted.If now the solenoid is de-energised the valve will be opened and, as aresult of this, fuel will flow from the chamber defined intermediate theplunger 51 and the abutment 54, and the restriction 57a will cause apressure drop. As the output pressure of the feed pump increases thepressure drop will also increase and at a predetermined value theplunger will be moved against the action of the spring 53 with theresult that the flow of fuel to the inlet port 23 will be restricted andthe quantity of fuel which can be supplied to the engine and hence thespeed of the engine will be limited. The degree of restriction dependsupon the speed of the engine and consequently a governing action iscreated which is additional to the action of the main governor. Thespeed at which the restriction is imposed depends on the force exertedby the spring and this may be adjusted by means of the adjuster 55 andthe setting of this will depend on the ratio of the gearing of thevehicle.

Although solenoid operation is preferred the valve member may be movedby mechanical or hydraulic means associated with the selector lever 47of the gearbox.

Owing to the fact that the fuel pressure which acts on the end of theplunger remote from the spring has to pass through a restriction definedbetween the plunger and the wall of the bore the rate at which theplunger can move in either direction is restricted. This is particularlyuseful because oscillation of the plunger is minimised when the outputpressure of the fuel pump varies rapidly.

In some vehicles a multi-ratio rear axle is provided in which case afurther switch or switches may be provided to cause de-energisation ofthe solenoid when a high gear is selected.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel pumping apparatus for supplying fuel to an internalcombustion engine and comprising a body part, and injection pump mountedwithin the body part and operable to supply fuel in timed relationshipto the engine, a fuel supply pump located within the body part, valvemeans for control-ling the output pressure of the fuel supply pump inaccordance with the rate at which the apparatus is driven, passage meansthrough which fuel flows from the supply pump to the injection pump, athrottle for controlling the rate of fuel flow through said passagemeans, operator adjustable speed responsive governor means fordetermining the setting of said throttle thereby to control the quantityof fuel delivered by the injection, a plunger slidable within the bodypart and operable to limit the rate of fuel flow through said passagemeans irrespective of the setting of said throttle, resilient meansbiasing said plunger to a position in which no limitation of the rate atwhich fuel is supplied occurs and means operable from the exterior ofthe apparatus to permit the pressure of fuel developed by the supplypump to be applied to the plunger to move it in opposition to itsresilient loading thereby to limit the rate of fuel flow when the speedat which the apparatus is driven exceeds a predetermined value.

2. An apparatus as set forth in claim 1 in which said plunger is mountedwithin a cylinder defined in the body part, a conduit through which oneend of said cylinder communicates with the supply pump, a restrictionthrough which the opposite ends of the cylinder are in communi cationwith each other, and the valve means operable from the exterior of theapparatus to permit fuel to escape from said other end of the cylinder.

3. An apparatus as set forth in claim 2 including an adjustable abutmentwhereby the force exerted by said resilient means on the plunger can bevaried.

References Cited UNITED STATES PATENTS 1,336,462 4/1920 Church "74-4722,641,238 6/1953 Roosa -123-140 2,719,437 10/1955 Nallinger 74-4723,209,613 10/1965 Potter 74- 472 10 3,286,543 11/1966 Porter 74-472 FREDC. MATTERN, JR., Primary Examiner.

W. I. KRAUSS, Assistant Examiner.

